This invention relates to throttling devices used as part of a pipeline or installed in other parts of fluid systems, in order to reduce high static pressure of a liquid or gas without the undesirable by-products of a high aerodynamic noise level in case of a compressible fluid such as natural gas coming from a high pressure gas well, or cavitation and erosion in case of a liquid. A typical liquid pressure reducing application would be boiler feed-water by-passing a feed-water pump under low load conditions, in order to keep the pump from being damaged. In applications like this, pressures as high as 6000 psi have to be reduced without the above mentioned adverse side effects.
Conventional devices employed for these purposes include perforated plates such as shown in U.S. Pat. No. 3,665,965, which generally perform satisfactorily. However, plates of this kind are very expensive to produce because all of the hundreds or sometimes thousands of small holes have to be drilled, a very time consuming effort. Stampings cannot be used because the thickness of the plates has to be more than two times a hole diameter, in order to withstand the stress in the metal caused by the hydrostatic pressure acting on the plate. Furthermore, undesirable resonance phenomena can occur with gaseous fluids, if the plate thickness is less than one hole diameter.
My invention overcomes these difficulties by use of stamped plates requiring essentially no machining and providing sufficiently large openings to accommodate the requirements set by the stamping die in relation to the plate thickness. Yet, the throttling flow passages can be kept small and narrow to ensure high energy losses or, in case of gases, high frequency of the produced aerodynamic noise (high frequency noise is better attenuated by surrounding pipe walls, i.e. produce less observable soundpressure levels outside of a piped fluid system). Any desired narrowness of the throttling flow passages of my invention can simply be determined by the selection of additional simple ring members or washers, which separate the stamped teeth-like configuration which provide vertical passage ways for the fluid.
Other objectives are to provide a compact fluid resistance device, which can be installed in existing piping systems by being clamped between a pair of line flanges and one whose fluid passages can easily be cleaned after being made accessible by a simple separation of a male and female member.
Yet, another objective is the provision of a fluid resistance device which has a relatively high flow capacity, yet offers maximum resistance. Such high flow capacity is possible with my teeth-like stampings, which provide up to 50% of the stamped annular surface area as vertical passage ways.